1. Field of the Invention
This invention relates to wheelchair lift for transit vehicles specially to an "Improved Power Unit" and Automated Folding Platform.
2. Discussion of Prior Art
Wheelchair lift previously refered to as "powered loading platform" in U.S. Pat. No. 4,140,230 to Pearson, Feb. 20, 1979 discloses electromechanical power unit by adopting ball screw and bevel gear and linkage assembly which results in a power unit box which is bulky in size, and requires intensive maintenance and is undesirably noisy. The platform of the prior art is only manually foldable.
Such manual operation of wheelchair lift platform which is intended for a disabled person requires assistance of a second person and is not by all means desireable; especially to those wheelchair occupants who are also independent drivers as well.
In the prior art the term "powered loading platform" used repeatedly implies to a lift with manually operated platform where as in my invention ,folding of the platform is fully automated as will be described in detail in the description of my invention.
Although my invention and the prior art share a minor physical resemblence, my invention greately differs in the novelty features. However, the common areas of similarity rests on:
a--Use of parallelogram linkage theorem which has been an academic principal in mechanics and kinematics text books and has a history of adoption in various fields for over 180 years. PA1 b--Segmented hinged platform which has also been in use in the military and the cargo air-crafts for many decades.
Obviously, neither prior art, nor my invention can solely rely explicitly on the above mentioned aspects of invention as a part of novelty features.